Problem: $ { \left[\begin{array}{rr}{0} & {1} \\ {3} & {1} \\ {2} & {-1}\end{array}\right]+\left[\begin{array}{rr}{4} & {-2} \\ {1} & {0} \\ {-1} & {0}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{0}+{4} & {1}+{-2} \\ {3}+{1} & {1}+{0} \\ {2}+{-1} & {-1}+{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{4} & {-1} \\ {4} & {1} \\ {1} & {-1}\end{array}\right]}$